Image display device, brightness control method and brightness control program

ABSTRACT

An image display device includes a display unit that is installed inside a finder window provided in a housing and displays images, an illumination unit that illuminates a space inside the finder window, an obtaining unit that obtains brightness of an outside of the housing, and a control unit that when the brightness obtained by the obtaining unit is a first brightness, sets the brightness of the illumination unit to a second brightness, and when the brightness obtained by the obtaining unit is a third brightness brighter than the first brightness, sets the brightness of the illumination unit to a fourth brightness brighter than the second brightness.

BACKGROUND

1. Technical Field

The present invention relates to an image display device, a brightnesscontrol method, and a brightness control program.

2. Related Art

As a digital still camera (DSC), there is known one mounted with anoptical finder (see JP-A-2007-33701). Also, instead of the opticalfinder, there is known a DSC mounted with an electronic view finder(hereinafter, referred to as an “EVF”). The EVF displays image datagenerated by an imaging element of the DSC on a liquid crystal screeninstalled in an inner space of a finder window of the finder.

In the DSC mounted with the EVF, finder image disorientation asdisclosed in JP-A-2007-33701 is particularly problematic. In otherwords, when a user continues to view images displayed on the liquidcrystal screen through the EVF, the user feels dizzy, seems to feeldisorientated, or feels an unpleasant pressure behind the eye. Thisdizziness, disorientation or discomfort (hereinafter, collectivelyreferred to as “disorientation”) is thought to be because the user feelsuncomfortable due to the EVF displaying images with a constantbrightness (brightness brighter than the ambient light) regardless ofthe brightness of the ambient light, or because a luminosity differencebetween the space containing the liquid crystal screen as the EVF andthe liquid crystal screen is great, or the like.

In the case of the optical finder, since the brightness of images whicha user views through the finder window of the finder is not brighterthan ambient light, the above-described “disorientation” is not greatlyproblematic. In addition, the EVF mounted in the DSC until now isrelatively low in terms of the luminance of the liquid crystal screen orthe resolution, and thus a user hardly feels “disorientated” asdescribed above. However, hereafter, as a user uses the EVF more andmore and luminance and definition of the EVF are increased, it isthought that the generation of the “disorientation” of a user is furtherproblematic.

SUMMARY

An advantage of some aspects of the invention is to provide an imagedisplay device, a brightness control method, and a brightness controlprogram, capable of reducing or eliminating disorientation of a user whoviews images displayed on a display unit.

According to an aspect of the invention, there is provided an imagedisplay device including a display unit that is installed inside afinder window provided in a housing and displays images; an illuminationunit that illuminates a space inside the finder window; an obtainingunit that obtains brightness of an outside of the housing; and a controlunit that when the brightness obtained by the obtaining unit is a firstbrightness, sets the brightness of the illumination unit to a secondbrightness, and when the brightness obtained by the obtaining unit is athird brightness brighter than the first brightness, sets the brightnessof the illumination unit to a fourth brightness brighter than the secondbrightness. According to the invention, the control unit makes theillumination unit bright if the outside of the housing is bright, andmakes the brightness of the illumination unit lowered if the outside ofthe housing is dark. That is to say, since the brightness of the spaceinside the finder window is adjusted according to brightness of ambientlight of the device, it is possible to reduce or remove that a userviewing images on the display unit through the finder window feels“disorientated” as described above.

The image display device may further include a determination unit thatdetermines whether or not the finder window is viewed, wherein thecontrol unit may increase the brightness of the display unit and thebrightness of the illumination unit as a time for the determination unitto determine that the finder window is viewed becomes longer. Accordingto this configuration, if the finder window is continuously viewed bythe user, the display unit and the illumination unit become graduallybrighter with the passage of time. Thereby, the eyes of the user viewingthe images on the display unit through the finder window become used tothe brightness of the display unit and the brightness of the spaceinside the finder window, and the user hardly feels “disorientated”described above.

The obtaining unit which obtains brightness of the outside of thehousing may be, for example, a photometry sensor which is provided inthe housing of the image display device and measures ambient light.

The image display device may further include photographing unit thatphotographs an outside of the housing and generates image data, whereinthe display unit may display images based on the image data generated bythe photographing unit, and wherein the obtaining unit may obtainbrightness of an outside of the housing based on the image datagenerated by the photographing unit. According to this configuration,even if the above-described photometry sensor is not intentionallymounted, it is possible to obtain brightness of the outside of thehousing a photographing unit which is typically equipped in a camera.

A user easily feels “disorientated” described above when viewing brightimages in a dark space. Therefore, it is preferable that at least wallsurfaces around the display unit of wall surfaces inside the housing arewhite. According to this configuration, since the wall surfaces aroundthe display unit in a space which the user views through the finderwindow are white, darkness in the space is reduced, and, as a result,the user hardly feels “disorientated.”

The technical spirit of the invention can be realized by other means aswell as the image display device. For example, an invention of a methodincluding process steps performed by the respective units of theabove-described image display device (a brightness control method) or aninvention of a program enabling predetermined hardware (for example, acomputer embedded in the image display device) to perform the functionsof the respective units of the above-described image display device(brightness control program) can be grasped as well.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a diagram schematically illustrating a DSC when seen from theside.

FIG. 2 is a block diagram illustrating a schematic configuration of theDSC.

FIG. 3 is a sectional view schematically illustrating an inside of afinder box.

FIG. 4 is a flowchart illustrating a process according to a firstembodiment.

FIG. 5 is a diagram illustrating an example of a table.

FIG. 6 is a diagram illustrating an example of a table.

FIG. 7 is a diagram illustrating an example of a table.

FIG. 8 is a flowchart illustrating a process according to a secondembodiment.

FIG. 9 is a flowchart illustrating a process according to a thirdembodiment.

FIG. 10 is a flowchart illustrating a process according to a fourthembodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the invention will be described withreference to the accompanying drawings.

FIG. 1 is a diagram schematically illustrating a DSC 10 according tothis embodiment when seen from the side. In FIG. 1, portions of theinternal configuration of the DSC 10 are denoted by chained lines. TheDSC 10 realizes, as one of its functions, a function as an image displaydevice according to the invention. An imaging lens 11 and an imagingelement 12 are schematically installed inside the DSC 10. The imagingelement 12 is an image sensor such as CCD or CMOS. A liquid crystaldisplay for a monitor (a monitor LCD) 13 is provided in the rear surfaceside of the DSC 10, and an EVF 14 is provided in the rear surface sideof the DSC 10 and at a predetermined position in the upper side of themonitor LCD 13. The EVF 14 is installed in a space (hereinafter,referred to as a “finder box FB”) formed inside a finder window 16 whichis provided in the rear surface side of a housing 15 of the DSC 10 andat a predetermined position in the upper side of the monitor LCD 13. TheEVF 14 corresponds to a display unit in the invention.

FIG. 2 is a block diagram illustrating a schematic configuration of theDSC 10. In addition to the above-described constituent elements, the DSC10 includes respective constituent elements such as a control unit 17,an imaging element driver 18, an external photometry sensor 19, an A/Dconverter 20, an illumination unit 21, an internal photometry sensor 22,an A/D converter 23, and an approach sensor 24. However, the DSC 10 doesnot necessarily include the respective constituent elements, and, foreach embodiment described later, there are necessary elements andunnecessary elements.

The control unit 17 has a CPU 17 a, ROM 17 b, RAM 17 c, and so on. TheCPU 17 a performs a process according to a predetermined program storedin the ROM 17 b, and thereby realizes an image process in the DSC 10 orcontrol of the entire DSC 10.

A subject image incident through the imaging lens 11 is formed on alight sensing surface of the imaging element 12. The imaging elementdriver 18 drives the imaging element 12 under the control of the controlunit 17. The driven imaging element 12 generates an electric signalcorresponding to a light amount of the subject image and A/D convertsthe electric signal to output digital image data. The imaging lens 11,the imaging element 12, and the imaging element driver 18 constitute animaging unit. The control unit 17 performs a predetermined image processsuch as color correction for the digital image data which is then outputto the EVF 14 or the monitor LCD 13.

The EVF 14 includes a liquid crystal panel 14 a and a backlight 14 bused as a light source of the liquid crystal panel 14 a. The EVF 14displays images on the liquid crystal panel 14 a based on the digitalimage data output from the control unit 17. The control unit 17 cancontrol brightness (luminance) of the backlight 14 b when displayingimages on the liquid crystal panel 14 a. The emitting luminance of thebacklight 14 b can be adjusted from 0% (minimal luminance) to 100%(maximal luminance) by changing a duty ratio, for example, when thebacklight 14 b is intermittently driven by PWM (pulse width modulation)control. Also, a screen size of the liquid crystal panel 14 a is smallerthan a screen size of a liquid crystal panel (not shown) constitutingthe monitor LCD 13. Although not shown in the figure, there is alsopresent a backlight corresponding to the liquid crystal panel of themonitor LCD 13.

The external photometry sensor 19 is provided at a predeterminedposition exposed to the outside of the housing 15 of the DSC 10, and isan obtaining unit which obtains brightness of the outside of the DSC 10.An output signal corresponding to a light amount measured by theexternal photometry sensor 19 is A/D converted by the A/D converter 20and then is input to the control unit 17. The illumination unit 21 isprovided inside the finder box FB and illuminates an inside of thefinder box FB. The control unit 17 can adjust brightness of theillumination unit 21 by, for example, PWM control. The illumination unit21 is constituted by, for example, LEDs.

The internal photometry sensor 22 is provided at a predeterminedposition exposed to the inside of the finder box FB and is an obtainingunit which obtains brightness of the inside of the finder box FB. Anoutput signal corresponding to a light amount measured by the internalphotometry sensor 22 is A/D converted by the A/D converter 23 and thenis input to the control unit 17. The approach sensor 24 is providedaround the finder window 16 and is a non-touch type sensor that detectsthe presence of a person. The approach sensor 24 can detect the approachof a person in a predetermined range very close to the finder window 16,and when detecting the approach of a person, outputs a predetermineddetection signal to the control unit 17. The control unit 17 candetermine whether or not the finder window 16 is viewed by a user, basedon the presence or not of the detection signal.

FIG. 3 is a sectional view schematically illustrating the inside of thefinder box FB including the EVF 14 and the like. In FIG. 3, for easyviewing, hatching or the like is not shown. In the example shown in FIG.3, the EVF 14 includes the liquid crystal panel 14 a installed at apredetermined position opposite to the finder window 16 in the finderbox FB, the backlight 14 b provided in the rear surface of the liquidcrystal panel 14 a, and a predetermined number of magnifying lenses 14 cprovided between the liquid crystal panel 14 a and the finder window 16.An LED 21 a as the illumination unit 21 is provided in a wall surface inthe finder box FB and in the wall surface in a predetermined rangebetween the magnifying lenses 14 c and the liquid crystal panel 14 a. Inaddition, the internal photometry sensor 22 is provided at apredetermined position between the magnifying lenses 14 c and the liquidcrystal panel 14 a.

A user easily feels “disorientated” when viewing a bright image in adark space. Therefore, in this embodiment, wall surfaces around at leastliquid crystal panel 14 a of the wall surfaces inside the finder box FBare white. In FIG. 3, a range of the white is shown as an example. Inthis way, since the wall surfaces around the liquid crystal panel 14 aof the wall surfaces inside the finder box FB are white, darkness aroundthe liquid crystal panel 14 a is alleviated, and, as a result, the userhardly feels “disorientated.”

Hereinafter, a plurality of embodiments regarding a configuration of theDSC 10 will be described.

First Embodiment

FIG. 4 shows a brightness control process mainly performed by thecontrol unit 17 when the EVF 14 is made to display images based on thedigital image data and is a flowchart illustrating a process accordingto the first embodiment. First, in step S100, the control unit 17obtains the brightness of the outside of the DSC 10 by driving theexternal photometry sensor 19. In other words, the control unit 17 makesthe external photometry sensor 19 measure the light amount of theoutside and obtains an output signal as a result of the measurement viathe A/D converter 20.

In step S110, the control unit 17 sets brightness of the EVF 14according to the brightness of the outside of the DSC 10 obtained instep S100. The brightness of the EVF 14 set here indicates a luminanceof the backlight 14 b. In this case, the higher the level of the lightamount indicated by the measured result (that is, as the outside of theDSC 10 becomes brighter), the higher the luminance set by the controlunit 17. In other words, when the level of the light amount indicated bythe measured result is a first level, the control unit 17 sets a secondluminance corresponding to the first level, and when the level of thelight amount indicated by the measured result is a third level higherthan the first level, the control unit 17 sets a fourth luminancebrighter than the second luminance. The control unit 17 sets thebrightness of the EVF 14 according to the measured result with referenceto a table stored in a predetermined memory such as the ROM 17 b inadvance.

FIGS. 5, 6 and 7 show examples of the table T. The tables T all define arelationship between an input value (the level of the light amountindicated by the measured result) and an output value (the luminance ofthe backlight 14 b). The table T in FIG. 5 has a characteristic that theoutput value increases in a stepwise manner according to increase in theinput value, and the table T in FIG. 6 has a characteristic that theoutput value increases linearly according to increase in the inputvalue. The table T in FIG. 7 has a characteristic that the output valueincreases non-linearly according to increase in the input value. Thecontrol unit 17 sets the luminance of the backlight 14 b using any oneof the tables T shown in FIGS. 5 to 7.

In step S120, the control unit 17 drives the backlight 14 b through PWMcontrol in order to come to the luminance set in step S110, therebyadjusting the luminance of the backlight 14 b. As a result, thebacklight 14 b emits light with a brightness according to the brightnessof the outside of the DSC 10 (the backlight 14 b emits light with a highluminance if the outside is bright, and the backlight 14 b emits lightwith a low luminance if the outside is dark). In this way, according tothe first embodiment, the brightness of the EVF 14 is also adjustedaccording to the brightness of ambient light of the DSC 10. For thisreason, the problem in the related art that, for example, since an imagereflected on the EVF is displayed with a high luminance regardless ofthe brightness of the actual scene even if the ambient scene around theactual user is dark, the user feels “disorientated”, is solved.

Although the control unit 17 obtains the outside brightness by drivingthe external photometry sensor 19 in step S100, the external photometrysensor 19 is not necessarily employed. In step S100, the control unit 17may obtain brightness of the outside of the DSC 10 based on the digitalimage data generated and output by the imaging element 12. That is tosay, the control unit 17 analyzes the image data to, for example,calculate an average luminance for the image data, and obtains thecalculated average luminance as the brightness of the outside of the DSC10. In addition, in step S110, the control unit 17 sets a luminance ofthe backlight 14 b corresponding to the brightness obtained in this way,using the tables having the input and output characteristics as shown inFIGS. 5 to 7. In this case, the above-described “level of the lightamount indicated by the measured result” is replaced with “the averageluminance for the image data.”

In this way, when the configuration where brightness of the outside ofthe DSC 10 is obtained based on the image data obtained by the imagingelement 12 is employed, there is no need for the external photometrysensor 19 for obtaining brightness of the outside of the DSC 10, andthus costs for the entire device are reduced. In the first embodiment,the illumination unit 21, the internal photometry sensor 22, and the A/Dconverter 23 are not used, and thus they can be omitted from theconfiguration of the DSC 10.

In addition, there is a case where immediately after the finder window16 is viewed by a user, the user's eyes are not accustomed to brightnessof the EVF 14 inside the finder box FB, the user feels images on theliquid crystal panel 14 a are brilliant or feels discomfort (feels“disorientated”). Therefore, the control unit 17 determines whether ornot the finder window 16 is viewed by a user, and brightness of the EVF14 may be increased as the time that the finder window 16 is viewed bythe user becomes longer. Specifically, for example, the control unit 17sets the luminance of the backlight 14 b in step S110 as describedabove, then, in step S120, does not take the set luminance as aluminance of the backlight 14 b immediately, and monitors the input of adetection signal from the approach sensor 24.

When the detection signal is continuously input, that is, during theperiod when it is determined that the finder window 16 is viewed by theuser, the luminance of the backlight 14 b gradually increases with thepassage of time, and finally the luminance of the backlight 14 bincreases to the above-described set luminance. In this configuration,the eyes of the user who views images on the liquid crystal panel 14 athrough the finder window 16 are appropriately used to the brightness ofthe liquid crystal panel 14 a, and the user hardly feels“disorientated.” Also, when the luminance of the backlight 14 bgradually increases with the passage of time, the method of the increasemay be stepwise, linear or non-linear. Also, in step S120, a luminanceof the backlight 14 b may be taken as the set luminance immediately, theluminance of the backlight 14 b may gradually increase with the passageof time during a period when it is determined that the finder window 16is viewed by a user based on the detection signal from the approachsensor 24, and finally the luminance of the backlight 14 b may have aconstant value.

Second Embodiment

FIG. 8 shows a brightness control process mainly performed by thecontrol unit 17 when the EVF 14 is made to display images based on thedigital image data and is a flowchart illustrating a process accordingto the second embodiment. First, in step S200, the control unit 17obtains brightness of the inside of the finder box FB by driving theinternal photometry sensor 22. In other words, the control unit 17 makesthe internal photometry sensor 22 measure a light amount and obtains anoutput signal as a result of the measurement via the A/D converter 23.

In step S210, the control unit 17 sets brightness of the EVF 14according to the brightness of the inside of the finder box FB obtainedin step S200. The brightness of the EVF 14 set here indicates aluminance of the backlight 14 b. In this case, the control unit 17 setsa high luminance to the extent that the level of the light amountindicated by the result measured in step S200 is high (that is, as theinside of the finder box FB becomes brighter). In other words, when thelevel of the light amount indicated by the measured result is a firstlevel, the control unit 17 sets a second luminance corresponding to thefirst level, and when the level of the light amount indicated by themeasured result is a third level higher than the first level, thecontrol unit 17 sets a fourth luminance brighter than the secondluminance. In the second embodiment as well, the control unit 17 setsthe brightness of the EVF 14 according to the measured result withreference to the tables T (FIGS. 5 to 7) stored in a predeterminedmemory such as the ROM 17 b in advance.

In step S220, the control unit 17 drives the backlight 14 b through PWMcontrol in order to come to the luminance set in step S210, therebyadjusting the luminance of the backlight 14 b. As a result, thebacklight 14 b emits light with brightness according to the brightnessof the inside of the finder box FB (the backlight 14 b emits light witha high luminance if the inside of the finder box FB is bright, and thebacklight 14 b emits light with a low luminance if the inside of thefinder box FB is dark). In this way, according to the second embodiment,the luminance of the backlight 14 b is adjusted according to thebrightness of the inside of the finder box FB, in such a way that abrightness difference between the brightness of the inside of the finderbox FB and the liquid crystal panel 14 a as the EVF 14 does notincrease. For this reason, it is possible to reduce or remove that auser feels “disorientated” due to the luminosity difference. In thesecond embodiment, the external photometry sensor 19, the A/D converter20, and the illumination unit 21 are not used, and thus they can beomitted as the configuration of the DSC 10.

Third Embodiment

FIG. 9 shows a brightness control process mainly performed by thecontrol unit 17 when the EVF 14 is made to display images based on thedigital image data and is a flowchart illustrating a process accordingto the third embodiment. First, in step S300, the control unit 17obtains the brightness of the EVF 14. In this case, the control unit 17can obtain the brightness of the EVF 14 based on any one or both of thedigital image data generated and output by the imaging element 12 andthe brightness of the backlight 14 b. For example, an average luminancefor the digital image data is calculated and the calculated averageluminance is designated as brightness of the EVF 14. Alternatively, aluminance indicated by a parameter set as indicating a luminance of thebacklight 14 b by the control unit 17 is designated as brightness of theEVF 14.

However, here, the control unit 17 obtains the brightness of the EVF 14based both the digital image data and the brightness of the backlight 14b. Specifically, regarding the average luminance for the digital imagedata and the luminance indicated by the parameter set by the controlunit 17, a predetermined coefficient for normalizing them is applied,and a result of summing or multiplying them is obtained as thebrightness of the EVF 14 itself.

In step S310, the control unit 17 sets the brightness (luminance) of theillumination unit 21 (LED 21 a) according to the brightness of the EVF14 obtained in step S300. In this case, the control unit 17 sets a highluminance to the extent that the brightness of the EVF 14 obtained instep S300 is high. In other words, when the brightness of the EVF 14 hasa first level, the control unit 17 sets a second luminance correspondingto the first level, and when the brightness of the EVF 14 has a thirdlevel higher than the first level, the control unit 17 sets a fourthluminance brighter than the second luminance. In the third embodiment aswell, the control unit 17 sets the luminance of the LED 21 a accordingto the brightness of the EVF 14 with reference to the tables T (FIGS. 5to 7) stored in a predetermined memory such as the ROM 17 b in advance.In this case, the above-described “level of the light amount indicatedby the measured result” is replaced with “the brightness of the EVF 14obtained in step S300.”

In step S320, the control unit 17 drives the LED 21 a through PWMcontrol in order to come to the luminance set in step S310, therebyadjusting the luminance of the LED 21 a. As a result, the LED 21 a emitslight with brightness according to the brightness of the EVF 14 itself(the LED 21 a emits light with a high luminance if the EVF 14 is bright,and the LED 21 a emits light with a low luminance if the EVF 14 isdark). That is to say, the brightness of the inside of the finder box FBis adjusted according to the brightness of the EVF 14 itself, such thata brightness difference between the brightness of the EVF 14 itself andthe brightness of the inside of the finder box FB does not increase.Therefore, it is possible to reduce or eliminate the problem that a userfeels “disorientated” due to the luminosity difference. In the thirdembodiment, the external photometry sensor 19, the A/D converter 20, theinternal photometry sensor 22, and the A/D converter 23 are not used,and thus they can be omitted as the configuration of the DSC 10.

In the third embodiment, the control unit 17 determines whether or notthe finder window 16 is viewed by a user, and brightness of the EVF 14and brightness of the illumination unit 21 may be increased as a timefor the finder window 16 to be viewed by the user becomes longer.Specifically, the control unit 17 sets a luminance of the LED 21 a instep S310 as described above, then, in step S320, does not take the setluminance as a luminance of the LED 21 a immediately, and monitors theinput of a detection signal from the approach sensor 24. When thedetection signal is continuously input, that is, during the period whenit is determined that the finder window 16 is viewed by the user, theluminance of the LED 21 a and the luminance of the backlight 14 brespectively gradually increase with the passage of time, and finallythe luminance of the LED 21 a increases to the luminance set in stepS310, and the luminance of the backlight 14 b increases to a luminanceindicated by the parameter set by the control unit 17. In thisconfiguration, the eyes of the user who views images on the liquidcrystal panel 14 a through the finder window 16 are appropriately usedto the brightness of the inside of the finder box FB and the brightnessof the liquid crystal panel 14 a, and the user hardly feels“disorientated.” Also, when the luminance of the LED 21 a and theluminance of the backlight 14 b gradually increase with the passage oftime, the method of the increase may be stepwise, linear or non-linear.Also, in step S320, a luminance of the LED 21 a may be taken as the setluminance immediately, the luminance of the LED 21 a and the luminanceof the backlight 14 b may gradually increase with the passage of timeduring a period when it is determined that the finder window 16 isviewed by a user based on the detection signal from the approach sensor24, and finally the luminance of the LED 21 a and the backlight 14 b mayhave a constant value.

Fourth Embodiment

FIG. 10 shows a brightness control process mainly performed by thecontrol unit 17 when the EVF 14 is made to display images based on thedigital image data and is a flowchart illustrating a process accordingto the fourth embodiment. First, in step S400, the control unit 17obtains brightness of the outside of the DSC 10 by driving the externalphotometry sensor 19. In other words, the control unit 17 makes theexternal photometry sensor 19 measure the outside light amount andobtains an output signal as a result of the measurement via the A/Dconverter 20.

In step S410, the control unit 17 sets brightness (luminance) of theillumination unit 21 (LED 21 a) according to the brightness of theoutside of the DSC 10 obtained in step S400. In this case, the controlunit 17 sets a high luminance to the extent that the level of the lightamount indicated by the measured result in step S400 is high (that is,as the outside of the DSC 10 becomes brighter). In other words, when thelevel of the light amount indicated by the measured result is a firstlevel, the control unit 17 sets a second luminance corresponding to thefirst level, and when the level of the light amount indicated by themeasured result is a third level higher than the first level, thecontrol unit 17 sets a fourth luminance brighter than the secondluminance. In the fourth embodiment as well, the control unit 17 setsthe luminance of the LED 21 a according to the brightness of the outsideof the DSC 10 with reference to the tables T (FIGS. 5 to 7) stored in apredetermined memory such as the ROM 17 b in advance.

In step S400, the control unit 17 does not obtain the outside brightnessusing the external photometry sensor 19 but may obtain the brightness ofthe outside of the DSC 10 based on the digital image data generated andoutput by the imaging element 12. That is to say, the control unit 17analyzes the image data to, for example, calculate an average luminancefor the image data, and obtains the calculated average luminance as thebrightness of the outside of the DSC 10. In addition, in step S410, thecontrol unit 17 sets a luminance of the LED 21 a corresponding to thebrightness obtained based on the image data in this way, using thetables having the input and output characteristics as shown in FIGS. 5to 7. In this case, the above-described “level of the light amountindicated by the measured result” is replaced with “the averageluminance for the image data.”

In step S420, the control unit 17 drives the LED 21 a through PWMcontrol in order to come to the luminance set in step S410, therebyadjusting the luminance of the LED 21 a. As a result, the LED 21 a emitslight with brightness according to the brightness of the outside of theDSC 10 (the LED 21 a emits light with a high luminance if the outside isbright, and the LED 21 a emits light with a low luminance if the outsideis dark). In this way, according to the fourth embodiment, thebrightness of the illumination unit 21 (the brightness of the inside ofthe finder box FB) is adjusted according to the brightness of ambientlight of the DSC 10. Thereby, the problem in the related art that a userviewing the EVF 14 feels “disorientated” due to a difference between thebrightness of the outside and the brightness of the inside of the finderbox FB, is solved. In the fourth embodiment, the internal photometrysensor 22 and the A/D converter 23 are not used, and thus they can beomitted from the configuration of the DSC 10.

In the fourth embodiment, the control unit 17 determines whether or notthe finder window 16 is viewed by a user, and brightness of the EVF 14and brightness of the illumination unit 21 may be increased as the timefor the finder window 16 to be viewed by the user becomes longer.Specifically, the control unit 17 sets a luminance of the LED 21 a instep S410 as described above, then, in step S420, does not take the setluminance as a luminance of the LED 21 a immediately, and monitors inputof a detection signal from the approach sensor 24. When the detectionsignal is continuously input, that is, during the period when it isdetermined that the finder window 16 is viewed by the user, theluminance of the LED 21 a and the luminance of the backlight 14 brespectively gradually increase with the passage of time, and finallythe luminance of the LED 21 a increases to the set luminance set in stepS410, and the luminance of the backlight 14 b increases to a luminanceindicated by the parameter set by the control unit 17. In thisconfiguration, the eyes of the user who views images on the liquidcrystal panel 14 a through the finder window 16 are appropriately usedto the brightness of the inside of the finder box FB and the brightnessof the liquid crystal panel 14 a, and the user hardly feels“disorientated.” Also, when the luminance of the LED 21 a and theluminance of the backlight 14 b gradually increase with the passage oftime, the method of the increase may be stepwise, linear or non-linear.Also, in step S420, a luminance of the LED 21 a may be taken as the setluminance immediately, the luminance of the LED 21 a and the luminanceof the backlight 14 b may gradually increase with the passage of timeduring a period when it is determined that the finder window 16 isviewed by a user based on the detection signal from the approach sensor24, and finally the luminance of the LED 21 a and the backlight 14 b mayhave a constant value.

Others

The present invention is not limited to the above-described embodimentsbut may have a variety of modifications without departing from the scopethereof. Of course, configurations combining the above-describedrespective embodiments may be implemented.

As an effect common to the respective embodiments, there is a powersaving effect in regard to the entire DSC 10 according to positive useof the EVF 14 by a user. That is to say, according to the respectiveembodiments, since the disorientation of a user using the EVF 14 isreduced or eliminated, it is thought that the user positively uses theEVF 14 instead of the monitor LCD 13. As described above, since in theEVF 14, the screen size of the liquid crystal panel 14 a is smaller thanthe screen size of the monitor LCD 13, if the EVF 14 is used more thanthe monitor LCD 13, power consumption in the DSC 10 is reduced and thusthe photographing is possible for a longer time using the DSC 10.

The configuration of the invention can be applied to various kinds ofdevices in addition to the camera equipped with the EVF. For example,the invention can be applied to a wearable display using an LCD in orderto adjust the brightness of the LCD or the brightness of the inside of aspace surrounding the LCD.

The entire disclosure of Japanese Patent Application No. 2010-030291,filed Feb. 15, 2010 is incorporated by reference herein.

1. An image display device comprising: a display unit that is installedinside a finder window provided in a housing and displays images; anillumination unit that illuminates a space inside the finder window; anobtaining unit that obtains brightness of an outside of the housing; anda control unit that when the brightness obtained by the obtaining unitis a first brightness, sets the brightness of the illumination unit to asecond brightness, and when the brightness obtained by the obtainingunit is a third brightness brighter than the first brightness, sets thebrightness of the illumination unit to a fourth brightness brighter thanthe second brightness.
 2. The image display device according to claim 1,further comprising a determination unit that determines whether or notthe finder window is viewed, wherein the control unit increases thebrightness of the display unit and the brightness of the illuminationunit as a time for the determination unit to determine that the finderwindow is viewed becomes longer.
 3. The image display device accordingto claim 1, further comprising a photographing unit that photographs anoutside of the housing and generates image data, wherein the displayunit displays images based on the image data generated by thephotographing unit, and wherein the obtaining unit obtains brightness ofan outside of the housing based on the image data generated by thephotographing unit.
 4. The image display device according to claim 1,wherein at least wall surfaces around the display unit of wall surfacesinside the housing are white.
 5. A brightness control method comprising:displaying images on a display unit installed inside a finder windowprovided in a housing; causing an illumination unit provided in a spaceinside the finder window to illuminate the space; obtaining brightnessof an outside of the housing; and when the obtained brightness is afirst brightness, setting the brightness of the illumination unit to asecond brightness, and when the obtained brightness is a thirdbrightness brighter than the first brightness, setting the brightness ofthe illumination unit to a fourth brightness brighter than the secondbrightness.
 6. A brightness control program enabling a computer toperform: displaying images on a display unit installed inside a finderwindow provided in a housing; causing an illumination unit provided in aspace inside the finder window to illuminate the space; and obtainingbrightness of an outside of the housing; and when the obtainedbrightness is a first brightness, setting the brightness of theillumination unit to a second brightness, and when the obtainedbrightness is a third brightness brighter than the first brightness,setting the brightness of the illumination unit to a fourth brightnessbrighter than the second brightness.